上游转子对下游静子叶片气动力的影响

为研究轴流压气机下游静子叶片非定常气动力的大小和频率的变化规律，采用在静子叶片表面埋设微型动态压力传感器的方法，在低速单级轴流压气机实验器上进行了静子叶片表面压力的测量。测量了不同轴向间距、不同转速下从近堵塞到近失速的宽广流量范围，并对所测得的静子叶片非定常气动力进行了离散傅立叶变换，以分析其频谱特性。实验结果表明：在转子尾迹的影响下，静子叶片表面的波动频率是转子的尾迹频率及其倍频。转子尾迹频率的高频分量对静子叶片吸力面前缘的影响比对其他位置的影响大。叶片表面的非定常压力和气动力随压气机流量、转速和轴向间距的变化而变化。     

用推力矢量控制技术改进超声速飞行器空气动力特性

为了提高某超声速飞机的空气动力学效率和机动性能，本文采用低阶的三维板块法和DATCOM半经验公式，在亚声速和超声速条件下，对不同马赫数和迎角情况计算了基本气动外形的飞机空气动力学特性、表面压力分布以及最大升力。此外还开发了一套软件以实现由引进的先进气动操纵面（如鸭翼等）控制的二维推力矢量技术。试验结果表明：气动操纵面结合推力矢量技术能够产生足够的低头力矩，且有能力满足高度机动飞行时的稳定性要求。此外，不论是亚声速还是超声速飞行，气动操纵面均可以提高气动效率5％-6％。     

用双激波模型计算风扇/压气机非设计点的性能

根据现代高速风扇/压气机内激波波系的真实结构,将适用于预测高速叶型激波损失的双激波模型引入基于基元叶片特性的流线曲率法程序,发展了一种用于预估高速风扇/压气机非设计点性能的方法。该双激波模型考虑了来流马赫数和攻角变化,较真实地反映了高马赫数风扇/压气机的实际工作状况,扩展预测风扇/压气机非设计点性能的能力。利用该模型,本文分别对一台叶尖马赫数达到1.4的大涵道比风扇和一台叶尖马赫数高达1.5的三级风扇的非设计点性能进行了计算,计算结果与试验结果保持了较高的吻合性。     

雷诺数对轴流风扇/压气机性能和稳定性的影响

介绍了一种预估轴流风扇／压气机特性和不稳定边界的方法。该方法采用考虑雷诺数影响的“基元叶栅法”计算轴流风扇／压气机特性，并利用C．C．Koch提出的“有效静压升系数法”预估轴流风扇／压气机的不稳定边界。为了验证方法的可行性，本文模拟了从地面到20 000m高空的雷诺数变化，对一个五级高压压气机在不同雷诺数下的特性及稳定性进行了计算分析。计算结果表明，轴流压气机的特性和稳定性都随雷诺数的降低而下降。     

面向绿色制造的高效冷却技术及其试验

绿色制造和高效加工是21世纪先进制造业的必然趋势,为实现绿色高效加工,本文提出了一种新型的绿色高效冷却技术——低温气动喷雾射流冲击冷却技术,通过低温气流运载少量冷却液以喷雾射流冲击的形式到达加工区实现强化换热,将加工区的换热水平提高到一个全新的水平.瞬态实验结果表明,在射流速度40 m/s、靶距10 mm的射流条件下,这种冷却方式可提供的临界热流密度高达60W/mm^2,相对于磨削发生烧伤的临界热流密度提高了6倍以上.     

燃烧室头部进气规律对煤粉燃烧效率的影响

用实验方法研究了火焰筒式煤粉燃烧室头部进气规律对燃烧效率的影响。通过对6种结构的头部配气方案的分析比较,得出了煤粉燃烧室合理的头部配气方案,为今后煤粉燃烧室的设计和工作状态的选择提供了重要的实验依据。     

一种整体式天然气压缩机气阀故障诊断技术研究CSCD

整体式天然气压缩机在石油化工领域广泛应用,压缩机的正常工作对安全生产具有重要意义。为了有效诊断整体式压缩机气阀部件的故障,采用了Daubechies小波基函数对ZTY470型整体式天然气压缩机气阀振动信号的分解重构原理,详细介绍了以振动信号的能量为故障特征的故障诊断过程。对气阀阀片断裂和弹簧断裂的故障振动信号进行了小波包分析,并与正常工作时的信号进行了对比。实验表明该方法能准确的进行故障诊断和故障定位,证明了对整体式天然气压缩机气阀故障诊断的有效性。     

Effect of protrusion amount on gas ingestion of radial rim seal

In this paper, the effect of different amount of protrusion on various parameters in rotor–stator system was experimentally studied by measuring CO₂ concentration and pressure, in order to obtain the optimal protrusion amount. The parameters of different dimensionless sealing flow were measured under the condition that the annulus Reynolds number was 4.39 × 10⁵ and the rotating Reynolds number was 1.05 × 10⁶. The results show that the change of the amount of protrusions has little effect on the static pressure in the cavity, and the static pressure change near the sealing ring is almost negligible. But the total pressure and sealing efficiency increase first and then decrease with the increase of the amount of protrusion. The variation of power consumption is the same. A complex vortex structure will appear at the high radius region when the protrusion is installed. On the other hand, the protrusion can effectively reduce the minimum sealing flow of the rotor–stator cavity. Furthermore, considering the sealing efficiency and power consumption, the best range of the protrusion amount is about 36. The ratio near this range can optimally balance the alleviation of the gas ingestion and the reduction of the power consumption.     

Aerodynamic performance enhancement for flapping airfoils by co-flow jet

Introducing active flow control into the design of flapping wing is an effective way to enhance its aerodynamic performance. In this paper, a novel active flow control technology called Co-Flow Jet (CFJ) is applied to flapping airfoils. The effect of CFJ on aerodynamic performance of flapping airfoils at low Reynolds number is numerically investigated using Unsteady Reynolds Averaged Navier-Stokes (URANS) simulation with Spalart-Allmaras (SA) turbulence model. Numerical methods are validated by a NACA6415-based CFJ airfoil case and a S809 pitching airfoil case. Then NACA6415 baseline airfoil and NACA6415-based CFJ airfoil with jet-off and jet-on are simulated in flapping motion, with Reynolds number 70,000 and reduced frequency 0.2. As a result, CFJ airfoils with jet-on generally have better lift and thrust characteristics than baseline airfoils and jet-off airfoil when C_μ is greater than 0.04, which results from the CFJ effect of reducing flow separation by injecting high-energy fluid into boundary layer. Besides, typical kinematic and geometric parameters, including the reduced frequency and the positions of the suction and injection slot, are systematically studied to figure out their influence on aerodynamic performance of the CFJ airfoil. And a variable C_μ jet control strategy is proposed to further improve effective propulsive efficiency. Compared with using constant C_μ, an increase of effective propulsive efficiency by 22.6% has been achieved by using prescribed variable C_μ for NACA6415-based CFJ airfoil at frequency 0.2. This study may provide some guidance to performance enhancement for Flapping wing Micro Air Vehicles (FMAV).     

多面体网格在静气动弹性计算中的应用

介绍了多面体网格技术在静气动弹性问题中的应用.基于M6算例和径向基函数插值法,探究了多面体网格的CFD计算效率和变形能力,使用AGARD445.6机翼进行了静气动弹性数值计算.结果表明,多面体网格具有计算效率高、变形能力强、计算结果准确等优点,可适用于静气动弹性问题的数值计算.